• Journal of Ginseng Research
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• 제4권2호
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• pp.197-221
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• 1980

Habitat observation, cultural experience of old and present plantation, weather factors in relation to crop stand and water physiology of root and leaf were reviewed. According to habitat observation ginseng plants love water but plate wit talus well grow at drained place with high moisture content in air and soil while ginseng plants were not found in dry or wet place. According to cultivation experience ginseng plants require abundant water in nursery and main field but most old planters believe that ginseng plaints are draught-loving thus require little water. The experience that rain especially in summer i.e unfavorable might be due to mechanical damage of leaves arid leaf disease infection, or severe leaf fall which is caused by high air temperature and coinsided with rain. According to crop stand observation in relation to weather factors abunsant water increased each root weight but decreased total yield indicating tile increase of missing root rate. Rain in summer was unfavorable too. Though rain in June was favorable for high yield general experience that cloudy day and rain were unfavorable might be due to low light intensity under shade. Present leading planters also do loot consider the importance of water in main field. Water content is higher in top than in root and highest in central portion of root and in stem of top. For seedling the heavier the weight of root is tile higher the water content while it reveries from two years old. Water potential of intact root appeared to be -2.89 bar suggesting high sensitivity to water environment. Under water stress water content severly decreased only in leaf. Water content of leaf appeared to be 78% for optimum, below 72% for functional damage and 68% for perm anent wilting. Transpiration or curs Principally through stomata in lower side of leaf thus contribution of upper side transpiration decreased with the increase of intensity. Transpiration is greater in the leaves grown under high light intensity. Thus water content is lower with high light inte nsity under field condition indicating that light is probable cause of water stress in field. Transpiration reached maximum at 10K1ut The decrease of transpiration at higher temperature seems to be due to the decrease of stomata aperture caused by water stress. Severe decrease of photosynthesis under water stress seems to be principally due to functional damage which is not caused by high temperature and Partly due to poor CO2 supply. Water potential of leaf appeared to be -16.8 bar suggesting weakness in draught tolerance. Ginseng leaves absorb water under high humidity. Water free space of leaf disc is %mailer than that of soybean leaf and water uptake appears to be more than two steps.

• The Korean Journal of Ecology
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• 제19권5호
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• pp.453-463
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• 1996

Diurnal changes of microclimatic conditions and tissue water relations were measured at two sites where Carpinus laxiflora and C. cordata were allopatrically distributed. The microclimatic conditions at a site where C. laxiflora was distributed produced severe water stress condition during summer months. Daily maximum temperature reached $30.4^\circC$ and the highest vapor pressure deficit was 1.31 KPa when 13 rainless days were continued. During this period soil water content decreased to below the field capacity even at a depth of 20 cm and xylem pressure potential also decreased to ­2.04 MPa. However, turgor potential was maintained more than 0.4 MPa. Patterns of stomatal conductance were changed with evaporative demand and soil water availability. On the other hand, microclimatic conditions at a site where C. cordata was distributed were moderate water strees condition compared with those at a site C. laxiflora was distributed. Though soil water content was maintained above field capacity C. cordata showed a remarkable decrease in turgor potential and stomatal conductance throughout the experiment. These results indicate that there is a difference in habitat characteristics between the two species and C. laxiflora is more resistant than C. cordata to water stress.

• 한국지반신소재학회논문집
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• 제14권4호
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• pp.35-43
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• 2015

원형모형실험을 통해 철도노반재료로 사용되는 흙을 대상으로 함수비 변화에 따른 침하관계를 평가하였다. 초기 함수비에서 침하량비($R_e$)는 2.08이었으나, 초기함수비보다 2배 이상으로 함수비가 증가되었을 때 침하량비($R_e$)는 4.06으로 4배 이상의 침하가 발생하였다. 또한 실제 공용중인 콘크리트궤도에서 계측된 강우데이타를 기반으로 약 1년여간 현장에 매설된 함수비 측정장비를 통해 장기 함수비 변화추이를 관찰하였다. 콘크리트궤도의 직하부에 위치한 함수비는 강우강도에 따라 변화가 거의 없는 수준이며, 사면부에서는 최대 강우강도 20mm/hr가 초과되는 경우 약 4% 정도의 함수비 변화가 생기는 것을 볼 수 있다. 이러한 변화정도를 볼 때 콘크리트 궤도의 경우 배수성능이 적절히 유지된다면 노반 내부의 함수비 변화는 강우에 대하여 영향이 매우 미비할 것으로 판단된다.

• Geomechanics and Engineering
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• 제23권2호
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• pp.139-149
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• 2020

Piles are widely used in structural foundations of engineering projects. However, the deformation of the soil around the pile caused by driving process has an adverse effect on adjacent existing underground buildings. Many previous studies have addressed related problems in sand and saturated clay. Nevertheless, the failure mechanism of pile driving in unsaturated soil remains scarcely reported, and this issue needs to be studied. In this study, a modeling test system based on particle image velocimetry (PIV) was developed for studying deformation characteristics of pile driving in unsaturated silt with different water contents. Meanwhile, a series of direct shear tests and soil-water characteristic curve (SWCC) tests also were conducted. The test results show that the displacement field shows an apparent squeezing effect under the pile end. The installation pressure and displacement field characteristics are sensitive to the water content. The installation pressure is the largest and the total displacement field is the smallest, for specimens compacted at water content of 11.5%. These observations can be reasonably interpreted according to the relevant unsaturated silt theory derived from SWCC tests and direct shear tests. The variation characteristics of the soil displacement field reflect the macroscopic mechanical properties of the soil around the pile.

• 한국농공학회지
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• 제45권5호
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• pp.133-139
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• 2003

Dredged soil from sea has much higher water content than liquid limit of clay and even if small loads apply, it will suffer a great settlement. Therefore it is very difficult to perform a consolidation test with general consolidation apparatus because of high water content. In this study Rowe Cell Apparatus consolidation tests have been performed with 1 remolding clay of water content 56% and 4 slurry clays of a water content of 100%, 120%, 133% and 150%. From the test results the consolidation characteristics such as compression index, secondary compression index and consolidation coefficient have been investigated with a variation of water content of dredged soil. The equations to get consolidation constants such as a compression index, a consolidation coefficient have been proposed with the field water content.

• The Korean Journal of Ecology
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• 제10권3호
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• pp.151-159
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• 1987

Relationships between soil factors and the growth of annual ring of Pinus densiflora grown on stony mountain were investigated at two sites of the different parent rocks: the one was formed by granite at Mt. Gwanag, Seoul and the other feldspar porphyry at Mt. Bipa, Daegu. The growth of annual ring was influenced by the physical factors of soil, such as soil depth, field caacity and water content of soil, rather than by the KDICical factors, such as total nitrogen, potassium, and calcium of soil. Of the soil factors affecting the growth of annual ring, soil depth, field capacity, water content of soil and organic matter closely interrelated with each other. All of these factors influenced water content of soil which might affect the water potential of Pinus densiflora leaves. In fact, the leaf water potential, affecting as the main factor for the growth of annual ring, of the pine grown in a deep soil was higher than that of the pine in a shallow soil.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.341-346
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• 2002

This study is intended to check the possibility to estimate water content by heat-drying method with variation of W/C and slump. According to the results, in case of electric range method, when water content is less than 165kg/m$^3$ in mixture, it is estimated more and in more than 165kg/m$^3$, it is estimated less. It shows that water content in gas burner method is estimated less by about 2kg/m$^3$. Also, estimated water content shows difference by less than 12kg/m$^3$ in electric range method and by less than 12kg/m$^3$ in gas burner method. Therefore, it is thinked that if tested without error from preparing a sample to calculating amount of water, water content will be estimated exactly in the construction field.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.367-370
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• 2005

In this study, air meter method and capacitance measurement method to apply economically at quality control of ready-mixed concrete among various unit water content measurement technique was selected. Then, it was evaluated estimating performance of unit water content according to the change of water-binder ratio and unit water content. Also, it was examined influence about error occurrence of unit water content by change of properties of used materials. Finally, based on this study, it was proposed fundamental data to utilize measurement technique of unit water content to quality control. of ready-mixed concrete in construction field.

• 한국농공학회지
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• 제36권2호
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• pp.123-131
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• 1994

Experimental studies were conducted to make clear the soil moisture environment under the condition of paddy-upland rotational fields by investigating water-table depths and soil moisture contents during growing season of crops in two kinds of soil. The following results were obtained. 1.Although water-table depths fluctuated with the amount of rainfall in the experimental field, it seemed that the variation of vater4able depths in the paddy-upland rotational, field was strongly affected by the condition of locations on paddy fields. 2.It is recognized that the concept of sum of excess water depth(SEWxx) and sum of excess water day(SEDxx) can be used to represent the soil moisture stress index due to the fluctuation of water-table depths. 3.The results of this study clearly indicate that drainage in paddy-upland rotational field to maintain an optimum soil moisture content must be made by introducing the concept of block drainage which needs both subsurface drainage and intercept drainage around a field. 4.Soil moisture contents were affected by both the amount of rainfall and water-table depths, however, the moisture content for top soil showed higher correlation with the amount of rainfall while that for subsoil with water-table depths.

• 한국농공학회:학술대회논문집
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• 한국농공학회 1998년도 학술발표회 발표논문집
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• pp.407-413
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• 1998

Considerable progress has been made in the application of time-domain reflectrometry(TDR) to measurement of soil water content. The TDR provides a means of monitoring the water content of soil over a wide range of values, in the field and in the laboratory The TDR measures the volumetric moisture content of the soil via a bureid sensor(probe). Probes can be buried and monitored remotely and an immediate result can be obtained. In addition to, the results are very reliable.